Smokers quit after brain damage
urge to smoke' could unravel the mysteries of addiction and provide
scientists with a new strategy for designing anti-smoking drugs.
Scientists from the University of Southern California (USC) and the University of Iowa have discovered nicotine addiction depends on a one-inch wide area of the brain called the insula. Damage to this area, like in the patient who suffered a stroke, can completely remove the body's urge to smoke.
"It is immediate. It's not that they smoke less. They don't smoke, period," said Antonio Damasio, director of the Brain and Creativity Institute at USC. It was Damasio who first proposed that the insula acted as a "platform for feelings and emotion."
Obviously, causing brain damage deliberately is not an option for treatment of nicotine addiction. However, scientists could use the discovery to monitor a smoker's progress while using other therapies or to develop new drugs that tackle the addiction.
It is also possible that the phenomenon could be applicable to future treatment of alcohol, drug and even food addiction, according to Antoine Bechara, senior author of the study, which is published today in the journal Science.
Bechara points out that the insula is a region of the brain that drug developers have paid no attention to. This research may change their thinking.
"There is a lot of potential for pharmacological developments," Bechara said.
He continued: "The insula also carries out lots of normal everyday functions so we would want to make sure we only interfere with functions that disrupt bad habits like smoking but not something vital like eating."
The link between the insula's role in emotion or feeling and a habit such as smoking shows that this area of the brain deals specifically with learned behaviours. As a result, it may be possible to target one without disrupting another.
The researchers studied patients with brain damage, all of whom had been smoking more than five cigarettes a day for more than two years when their brain damage occurred. Of the 69 patients studied, 19 had damage to the insula. Of those, 13 had quit smoking.
The patients stopped so quickly and without difficulty or relapse that Bechara and his colleagues concluded that the insula damage reduced the urge to smoke rather than reducing the pleasurable feeling associated with smoking.
Bechara noted that another possible approach to treating smoking addiction might be to use transcranialmagnetic stimulation: inducing weak electrical currents in brain tissue to disrupt the insula's activity, although currently this technique can not penetrate deep enough to affect the insula.